1) Field of the Disclosure
The disclosure relates generally to fuel vent systems in aircraft and other craft, and more particularly, to a vent dam configuration and method for use in a structural fuel vent stringer system in an aircraft.
2) Description of Related Art
Composite structures are used in a wide variety of applications. In aircraft construction, composites are used in increasing quantities to form the fuselage, wings, tail section, and other components. For example, the wings may be constructed of composite skin members to which stiffening elements, such as stringers, may be coupled to increase the bending strength and stiffness of the skin member. The stringers may extend in a generally span wise direction along the wing. The stringers may be bonded to the skin members and may be configured to carry bending loads or loads that are oriented substantially perpendicularly relative to the skin member.
Stringers may be provided in a wide variety of cross-sectional shapes. For example, a stringer cross-section may comprise a plurality of composite plies formed in a hat section configuration having a base portion and a pair of webs extending outwardly from the base portion. The base portion may comprise a pair of flanges to facilitate coupling (e.g., bonding) of the stringer to the skin member, such as the upper and lower wing skins of a wing. The hat section stringer may include a cap which interconnects the webs and encloses the hat section in order to increase the torsional rigidity of the stringer.
The stringers in a wing may extend from an inboard section of the wing to an outboard section of the wing. The stringers may include purely structural non-vent stringers and stringers that serve both as structural and system elements, such as vent stringers. Both types of stringers provide a primary load carrying function. The vent stringers may provide a secondary function by acting as a conduit for venting fuel and fuel vapors from the inboard sections of the wing fuel tanks to surge tanks. The vent stringers may include several vent dams that serve as fuel tank boundaries or barriers to ensure that the fuel and fuel vapor flow travels in the desired direction. Known vent dams exist. Such known vent dams may be made of sheet metal and have a flat plate surface attached at 90 degree angles to four side wall flanges. Because such known vent dams only act to block fuel flow, the fuel flow can impinge on an upper wing skin when entering the vent stringer and then must change direction by 90 degrees to flow down a vent stringer channel. Moreover, when the fuel flow enters the vent stringer, the fuel flow can impinge on the vent dam. Such fuel flow impingement on the upper wing skin and the vent dam, as well as an instantaneous 90 degree change of flow direction can result in turbulence and pressure drop or loss. Such pressure drop or loss can result in higher structural loads and a decreased refuel rate.
Accordingly, there is a need in the art for an improved vent dam configuration and method for use in a vent stringer system that provides advantages over known vent dam configurations and methods.